June 2018 - Darwin-kernel - lists.apple.com

Re: Debugging kext in lldb. Reading cpu_data_t offset 0x18 using %gs base address.
by Slava Imameev 17 Jun '18

17 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=GIhViwCyDVG1m81Zpy6LaIwyyeXhlZYcYzkXaI5I8bM=; b=pjPoc22dV07rWdymtfH6YGxhGhnHyA0EIuNthKM4EtX2C4V7DRRYqtBtInfBappftt sKll1xl0siB00MPEfK2C/1DmTEda5Uu6ZEVpyt2scyhZxNRzEGpVlln1wV8GYCkXYJbC VbGj6INF/hV0COolkqld1Iqi88QY/AdUCIybXn8+Qe2iiMM5cMUBB/7nap68TS6CpJam KKa40wjYy6WJJelyXFjJ9zEsqfWPQCYqhXAUSmTIG7lxTObSIc00cLG4Kq03aA0fue6N Fjtfs/94igC72v2SJtoLb9OGUsOEvZzjwjn1hnPX/YSZPH2XiaXuWh8zfJc4PhyntsFD 898Q== Hi, The cpu_preemption_level values were altered by the panic code. The actual values might be calculated by subtracting 3 from the cpu_preemption_level value for a CPU that panic'ed (panic_trap_to_debugger, kdp_i386_trap increase it) and 1 for other CPUs(a value is increased when processing IPI / NMI sent to freeze CPUs). That said the CPU's preemption level for a cpu that called msleep() was -1 before calling panic() and 0 for another cpu. The showcurrentstacks command has a bug by reporting values altered either by panic() or a kernel debugger code. _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Re: Debugging kext in lldb. Reading cpu_data_t offset 0x18 using %gs base address.
by Slava Imameev 16 Jun '18

16 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=GqdFb3WrqUgndm6kFP5DDNlrlnuN+87PKJtrCTsj+mg=; b=Rb0O9xC6fMGaebKgOI+G5TPVtqKlqRovqhgvwV0KnCKW99e/gGDkkZ07DY8mhfrcYn /HaSzStTSmqeVYL01KbD98TRohkbtoqI0KNdEbVwX2mXNBt50bpIPBnrP1hjo9qf+ADD 4lGMkFCJSoKUznj5M1Hxuo4RO2YAW0x2c2kxVbL23VOOvdR8NPsm+YMGx7Hhud2UsBPO YeYh+3CH8idDsYzhwXrTXQ1Umo4abIZYXpaAIe4ewwo2K4mcNLrNHVPP3UQRSI3Uku8o Oge3MxxUcLUG5SIuBa+vyewUpNW40wUQ0OrNUO/c13kkA/hXPHPIVoIo9n67CNLL9ZYA ieRQ== Hi, The GS register doesn't contain a virtual address for a segment. The GS register contains an offset into a GDT that contains segment descriptors. Actually, you don't need to access per-CPU data this way. Per-CPU data can be found by dereferencing elements from an array of pointers cpu_data_t *cpu_data_ptr[MAX_CPUS] For example, per-cpu data for a core which has been assigned an index 0 (lldb) p *cpu_data_ptr[0] (cpu_data_t) $2 = { cpu_this = 0xffffff800ec0c900 cpu_active_thread = 0xffffff8019e017b0 cpu_nthread = 0xffffff8019e017b0 cpu_preemption_level = 4 cpu_number = 0 cpu_int_state = 0xffffff801604be40 cpu_active_stack = 0xffffff8016048000 cpu_kernel_stack = 0xffffff801604bfb0 cpu_int_stack_top = 0xffffff8081a2a000 cpu_interrupt_level = 1 cpu_signals = 0 cpu_prior_signals = 0 .... The above assumes that you have loaded a kernel dump or attached to a live system with valid kernel symbols. If you are not sure on which core a kext is running use showcurrentstacks command. Regards, Slava Imameev On Thu, Jun 14, 2018 at 6:14 PM, Zohar Cabeli <zohar.cabeli(a)gmail.com> wrote: > Hi, > > I was wondering if you could give me some direction in lldb issue I'm > currently struggling with ... > > I've got a kext that produce panic for "preemption level -1" in macOS > Mojave (10.14), and I'd like to further investigate the issue. > It looks like preemption_level is read from the per-cpu data which that be > parsed using cpu_data_t struct (defined in xnu cpu_data.h). > > However, it seems like the memory is inaccessible using memory read of > %gs+0x18: > > register read gs > > gs = 0x000000009da40000 > > > memory read 0x000000009da40018 > > error: kdp read memory failed (error 4) > > perhaps there is another way of reading the cpu data ? > > > I also tried another approach by looking how could the preemption level be > negative. I guess that when using spin lock, it blocks the preemption of > the cpu... however, I've tried to look for such locks in all threads (using > `showallstacks` lldb command) but couldn't find any. > > Perhaps do you know better way to checking in lldb if spin lock is > currently active on any cpu ? > > Thanks, > Zohar > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/darwin-kernel/ > slava.imameev%40gmail.com > > This email sent to slava.imameev(a)gmail.com > > _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Debugging kext in lldb. Reading cpu_data_t offset 0x18 using %gs base address.
by Zohar Cabeli 14 Jun '18

14 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=XJ9+6R+Db1nDjc1/skFkYT6sB0EomS8BjZcskfbWC7k=; b=EM4usWT6nAQRDuo6ANJmPQENLqZnRNBF38MZioIcpwJLMb37l5YMVOL7ysRVwABIK4 EbbdxSetoM2AJ+5KV4LxKclvff6LztlTktm1GqywVOhovSjUj77l1Bx+bHle0dyveGCt IjvRBF/GKLtcR9cRfDZp8UhQdTmwiMYBwRBsscqaiXKNnAMWduMWLP/WVy2XLsedQ7Cr MXxA0unCg4qzCR1kEADuT3DOkl6qGvwwQjKnpmeCAPvtJD2vbOy2ss4G0w3Vn3lBJFoq a3mJHJte/7h+5CB3agecrrBoXYAhx95CSpLLUIudNIuhMwkKiLMGZW6iNCxCBS2UYSYQ ffWQ== Hi, I was wondering if you could give me some direction in lldb issue I'm currently struggling with ... I've got a kext that produce panic for "preemption level -1" in macOS Mojave (10.14), and I'd like to further investigate the issue. It looks like preemption_level is read from the per-cpu data which that be parsed using cpu_data_t struct (defined in xnu cpu_data.h). However, it seems like the memory is inaccessible using memory read of %gs+0x18: register read gs gs = 0x000000009da40000 memory read 0x000000009da40018 error: kdp read memory failed (error 4) perhaps there is another way of reading the cpu data ? I also tried another approach by looking how could the preemption level be negative. I guess that when using spin lock, it blocks the preemption of the cpu... however, I've tried to look for such locks in all threads (using `showallstacks` lldb command) but couldn't find any. Perhaps do you know better way to checking in lldb if spin lock is currently active on any cpu ? Thanks, Zohar _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Re: XNU source code for macOS Mojave developer preview
by Andreas Fink 09 Jun '18

09 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com we are at 10.13.5 officially released. so the sources are two release beyond. And yes if you want to be up to date on the game, having sources of the betas would really be important to be ready for the next major releases. One thing for example is the introduction of APFS all over the place while the file format isn't even documented. > On 9 Jun 2018, at 16:17, Amanda Walker <amanda(a)alfar.com> wrote: > > On Jun 9, 2018, at 6:27 AM, schrott_07(a)t-online.de wrote: >> Hello everyone, >> >> First of all I'm completely new to mailing lists, so please correct me if >> I'm doing something wrong. Now to my question: >> >> I've started to tinker a bit with the macOS Mojave developer preview, but >> unfortunately there's no source code for its version of XNU available (in >> fact opensource.apple.com hasn't been updated for anything higher than >> 10.13.3 yet). Is there any way I could get my hands on the source code? > > Usually source code is only released by Apple after an official macOS > release, not for developer previews or betas. > > —Amanda > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/darwin-kernel/afink%40list.fink.org > > This email sent to afink(a)list.fink.org _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Re: XNU source code for macOS Mojave developer preview
by Amanda Walker 09 Jun '18

09 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Jun 9, 2018, at 6:27 AM, schrott_07(a)t-online.de wrote: > Hello everyone, > > First of all I'm completely new to mailing lists, so please correct me if I'm > doing something wrong. Now to my question: > > I've started to tinker a bit with the macOS Mojave developer preview, but > unfortunately there's no source code for its version of XNU available (in > fact opensource.apple.com hasn't been updated for anything higher than > 10.13.3 yet). Is there any way I could get my hands on the source code? Usually source code is only released by Apple after an official macOS release, not for developer previews or betas. —Amanda _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Re: XNU source code for macOS Mojave developer preview
by Michael Tuexen 09 Jun '18

09 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com > On 9. Jun 2018, at 06:27, schrott_07(a)t-online.de wrote: > > Hello everyone, > > First of all I'm completely new to mailing lists, so please correct me if I'm > doing something wrong. Now to my question: > > I've started to tinker a bit with the macOS Mojave developer preview, but > unfortunately there's no source code for its version of XNU available (in > fact opensource.apple.com hasn't been updated for anything higher than > 10.13.3 yet). Is there any way I could get my hands on the source code? In the past, Apple released the source code sometime after the OS was released. Sometime can be a matter of weeks or months... Best regards Michael > > Regards, > notiflux > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/darwin-kernel/michael.tuexen%40lurc… > > This email sent to michael.tuexen(a)lurchi.franken.de _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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Re: XNU source code for macOS Mojave developer preview
by Richard L. Hamilton 09 Jun '18

09 Jun '18

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=6AMqBIWZv/xBb6r+lFVMRyPa8c2fq/LOgJf+IJd72u8=; b=ckawfexi3eih2hAnsKdP85OaB2fBxb+1wtpivnfX2kPDO5VMtdksZIj53VTxnS5YIJ ga6rfGfELvIbW0uUw05wsLngmqMikBwyZ8b5ciefB6Ks4MvL5rJNexUwJdCdi/dIBrZ/ z6gqk6qocihbai3EJL3+s5+18mbpIEQR14SD/D0yOR5KIiTOjMX96KXnrZ94nbInE1an JAXcHnw12zxY4mOARQ8Iwp4S5k9tE0+BulUQOj2jHGVv67qH0CHJw7XNElBOlFCztL1k wvX3b1t2dnuiR9hh/m3Y5hkGsjLS94G9pGOvpMXPu8Kx/kleYiu6Q0kFvVQ+LhC0DNkS vkPQ== If there's anyone from Apple here, I very much doubt they can decide to give out a copy of something that hasn't been released yet. As you say, they're not even up to the current public release. It's been like that for a long time, that they're always a bit behind; quite possibly the work involved in deciding what can and can't be released and getting it out is lower priority than actually coding, testing, packaging, etc. I've never seen publicly available source for a macOS version in beta. If for example your employer had a privileged relationship with Apple, you might be able to get it that way if you needed it for work; otherwise, I have my doubts that you'll be able to do more than wait like the rest of us. Anyone know whether paid developer program members can get earlier source access? I haven't seen any evidence of that, but I'm not one, so I might not have. > On Jun 9, 2018, at 06:27, schrott_07(a)t-online.de wrote: > > Hello everyone, > > First of all I'm completely new to mailing lists, so please correct me if I'm > doing something wrong. Now to my question: > > I've started to tinker a bit with the macOS Mojave developer preview, but > unfortunately there's no source code for its version of XNU available (in > fact opensource.apple.com hasn't been updated for anything higher than > 10.13.3 yet). Is there any way I could get my hands on the source code? > > Regards, > notiflux > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/darwin-kernel/rlhamil2%40gmail.com > > This email sent to rlhamil2(a)gmail.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists… This email sent to site_archiver(a)lists.apple.com

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XNU source code for macOS Mojave developer preview
by schrott_07＠t-online.de 09 Jun '18

09 Jun '18

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